Underreamer



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A. ALLIISUN\ UNDERREAMER Filed July 18, 1923 4 Shee-hs-Sheei: 55'

. may 55, W25. 1153mm I A. ALLEfiQIN UNDERREAIVIER Filed July 18, 192% 4 Sheets-Sheet 4 i? M 55 -17 F} T8 23 a .12 f 29 62 1? J L w ill is imposed upon the cutter.

resented May 5, 1925.

' UNITED, STATES PATENT OFFICE.

aucrnun ALLISON, or NIAYW' D, CALIFORNIA, ASSIGNOR T0 WILLIAM w. wILsON,

OELOSANGELES, CALIFORNIA.

- UNDERREAM ER.

Application filed July is, 1923. Serial No. 652,455.

L'ficcllwhom it may concern: i

llc it known that IQARTHUR ALLIsoN, a

ritizen of the United States, residing at lilaywood, in the county "of Los'Angeles,

" tate of California, have invented new and useful Improvements in Underreamers, of which the following is a specification.

This invention relates to underreamers for use in well drilling. Aside from certain general objects of the invention; which in- (Elude such Objects as simplicity and effectiveness of "construction and operation, ready removal of the cutters for sharpening or replacement, positiveness of action, etc; i may particularly mention certain objective 'leatures ofmy invention.

It is a primary object of my invention, and a feature of my underreamer, that the cutters are so interlocked with each other and with the body of the underreamer, as to be held solidly and firmly upon the body against all strain to which the cutters are subjected. This interlocking feature of my underreamer is an important one, both structurally and operatively. Each of the cutters bears inwardly against the body; and each ofthe cutters bears outwardly against the other cutter; and by this means the two cutters are locked to each other and locked to the body. Anyinward thrust upon either of the cutters is transmitted directly to the body and any outward thrust upon either of the cutters is transmitted to the other cutter, and then, through that other cutter, transmitted directly to the body. The transmission of such-strains from the cutter to the body is short -and;direct; the points at which the cutters are support- (Or-interlocked with themselves and with the bodyare close to the point where strain I embody these features of my invention preferably in an underreainer characterized the body between its forks. The eXpand by having a body with a lower bifurcated end; the cutters lying alongside each other (overlapping each other) in the space of ing and contracting actions, of the cutters are caused, in this specific form, by afmeans extending across the fork space, preferably in the form of a bolt or pin. only performs the function of causin the expansion and contraction of the cutters,

but also performs the function ofstructur-. ally connecting the two forks so as to com- This bolt notbine their strengths against any lateral force of this description, reference is had toxthe accompanying drawings in winch- Fig. 1 is a longitudinal sectional View of the lower part of the underreamer, in its expanded or operative condition; Fig. 2 is a similar view showing the parts in their contracted position within the well casing; Fig. 3 is a/side elevation of the lowerpart of the reamer; Fig. 4 is a bottom plan view with thecutters in'expanded position; Fig. 5 is a similar view with the cutters contracted; Fig. 6 is a horizontal section taken on line m-w on Fig. 1; Fig. 7 is a vertical section taken on line ca -er of Fig. 1; Figs. 8 and 9 are perspective views of the cutters; Fig. 10 is a side elevation, corresponding, in aspect and position of the parts, to Fig. 2; Fig. 11 is a horizontal section on line wm on Fig. 1; Fig. 12 is'a side elevation. of the lower part of the body, a portion being broken away for purposes of illustration and Fig. 13 is'a perspective of the lower end of the spring actuated mandrel which carries the cutters.

' In the drawings the numeral 2 designates the body of the underreamer, which may be equipped at its upper end with any of the usual means for connection with string of drilling tools. tudinal bore 8 to accommodate the mandrel 4' and spring 5. Spring 5 rests upon the key 8 which extends. across the body through the slot 6 and extends through a slot 7 in mandrel 4, slot 7'being of sufiicient length to allow the suitable vertical motion of the mandrel. The key 8 is held in place by suitable pins 9 through the ends of the key, the pins .resting in transverse slots or grooves 10 in the surface of body ,2. The upper end of spring 3 bears against Washer upper end of mandrel 4.

The body has a longi- The spring and. mandrel construction herein described is merely typical; any other suitable structure may be substituted for this one without altering the invention. so fa as the invention'is concerned the only function ofthe spring mandrel is merely to raise and support the cutters.

The lower end of mandrel 4: is suitably terminated to carry the cutters. For instance, it may terminate in an eye '13 which carries a bolt 16 projecting through transverse bores of the two cutters; and the eye 13 preferably fits snugly in the socket 14 and against the circular wall 14 thereof, in the cutters. The cutters are thus supported both by the fitting .of eye 13 in the sockets 14 and also by the pin 16. To permit-the swinging action of the cutters in contracting I and expanding the upper part of the socket let is cutout, asindicated at 14, (see Fig. 9) to make room for the mandrel 4 where it enters the socket.

The lower end of body 2 is forked or bifurcated, formingforks 2 and 2 with a fork-space'between them, ,said fork-space extending laterally through the lower end ofthe body from side'to side and open at the lower end. The inner faces of the forks are accuratelymachined to form fiat, ver tical opposite bearing surfaces 1ft; and the flat verticalshanks S of the cutters lie be- .tween these surfaces alongside each other,

overlapping each other between the forks 2 and 2 with the external surfaces S of the shanks bearing against the surfaces 17, the internal surfaces S of the shanks bearing against each other, and the shanks being confined laterally between two forks. On

' each side of the body and at each side of the fork-space, the body is machined away to provide the vertical opposite surfaces l'f, which make inthrust surfaces, against which the cutters bear, as hereinafter described. This machining also forms the downwardly facing shoulder surfaces 18 which take the upward end-thrusts of the cutters.

The two forks 2 and 2 'are structurally interconnected by a pin or bolt 19. This pin 19 has ahead 19 with a square socket hole 19, the head fitting in one of the forks against a shoulder 19. The other end of pin 19 carries a nut 20 fitting in recess 22; and the nut draws down against a shoulder 21. A sleeve 19 around pin 19 acts as a spacer between the furcations 2 and 2".

'l/Vhen nut 20 is screwed down tightly the two furcations are then rigidly and strongly connected to -act effectually as a single structure against any stresses tending either to move them toward or away from each other.

Pin 19 preferably fits the furcations tightly. The shanks S of the two cutters are in the general form of flat rectangular blocks: and

each shank is provided with a vertical slot 23 terminating in an upper offset diagonal slot 24. In the normal expanded position of the two cutters, pin 19 stands in the lower ends of slots 23; but when the cutters are moved downwardly they move inwardly when the upper slots 24 come into register with thepin 19; the pin standing in the 7 \of'these slots 23 and 24; and the slots are preferably of such shape as to provide for an abrupt expansion of the cutters upon theirinitial upward movement, and then to provide for a long straight upward sliding movement of the cutters in their expanded position. This provision is niadc for the. purpose of allowing the meet relatively large bearing surfaces for the cutters and allowing the long vertical movement of the expanded cutters necessary for the engagement of the cutters with said bearing surfaces. It will be understood that the cutter expanding means herein described (the pin and slots) is merely typical and indicative of means which may be used within the broader aspects of my'invention; and I do not necessarily limit myself to such means.

The lower ends of the cutter shanks are beveledaway, as shown at 25; and each cutter body B is correspondingly diagonally recessed as shown at 26, each recess 26 receiving the lower diagonal'edge of the other shank when the cutters are contracted; and

the diagonal spaces or passages between the recess bottoms 26 and diagonal end surfaces 25 form water courses for the passage of water for keeping the cutting ends of the cutter bodies B free from-accumulation of earth. \Vhen the cutters are in their collapsed position (see Fig.2) the lower inclined surfaces 25 fit into the recesses and fit against, or close to, the surfaces 26. These inclined surfaces so interactare placed at suchanglesas to allow the free relative movements of the cutters between the positions shown in Figs. 1 and 2; and at the same time the construction allows of the proper eigtension of the cutter shank to put a suitable amount of metal below the lower end of slot 23 (at the point denoted 25 in Fig. 1) for strength; and allows of the proper downward extension of the shank behind the body B to properly support the body. And. further, the interengagement of the lower diagonal edges of the shanks in the recesses ties the two cutters together laterally when the cutters are collapsed.

The detailed formationofeach cutter is best shown in Figs. 8 and 9. Shank S of each cutter is in the general form of a rectangular block with the laterally and downwardly projecting body 13 at its outer edge. It will be noted that the body 1) is not centrally located upon the shank. but projects laterally from the shank more at one side than-at the other;- so that, when the two shanks S are in proper position overlapping each other in the bifurcated end of the underreamer body, the cutter bodies B will be opposite each other as shown in the various views. The inner face of each cutter body B is provided with inwardly facing surfaces 27 which are vertical when the cutters are expanded; and when the cutters are expanded and then moved up these surfaces 27 then bear inwardly against the lower ends of bearing surfaces-17. At the same time, when thecutters are expanded, two overhanging shoulder surfaces 3 1, on'the inner sur-- faces of the cutter shanks, iiiterengage, one with the other, in such a manner as .to limit the relative outward movement of the cut ters. The formations of the shoulder surfaces 34 is shown in the various-sectional views. Whenthe cutters are in their upper expanded position each cutter body. bears directly inwardly against bearing surfaces:

17 at a'point on the backside of the cutter .body and close to its lower cutting end; so i that anyinward strain tending to crush the cutters inward-1y is immediately and shortly 1 transmitted to the body. At the same time any strain which tends to spreadthe cutters apart is transmitted immediately to the cutters thereby opposed. Any outward strain on either-cutter is immediately-transmitted to the other cutter. and then to the body. The interlocking of the cutters has the effect of causing the inward bearing of one cutter to form a means for resisting the outward movement of the other cutter, as

well as for resisting the inthrust of the cutters under an inward crushing strain. This interlocking of the cutters, in their expanded position, is a particular featureof my underreamer, and is one which makes it strong and durable. In fact, the ci tters as firmly held as if they were embedded in the body itself;and, at the same time, my method of cutter interlocking does away with the necessity of cutting special ways,

etc. in the body and thereby provides that the body shall be left in its fullest possible strength. i

When the. cutters are in their expanded position their upper end surfaces 31 shoulder up against the down thrust surfaces 18 of the underreainer body; and the upthrust of the euttersis thereby taken. Any

:side thrust upon the cutters is taken by the forks 2" and 2 It will be noted that the shanks S of the cutters fit snugly and sub- ,stantially fill the space between the forks;

and, the forks being rigidly connected by the bolt 19, any side thrust upon either cutm 'ter'is transmitted to and'borne by the forks.

In fact, the. structurally interconnected forks and the snugly fitting shanks form an almost solid structure very strong against lateral displacement. The shanks being wide, they not only'give agood lateralbearing on the body, but are also strong in :1

lateral direction. Any displacement of the upper end of the cutter shanks is prevented not only by the interlocking of the cutter shanks (which-interlock, it'will be noted, extends almost throughout the whole vertical length of the cutter shanks) and by the inward bearings of the cutter bodies upon the underreamer body, but is also prevented by theupward projection of the lugs 31, on the upper endsof the shanks, into bore 3 of the body, fitting preferably somewhat easily aise be prevented by the fitting 'of lugs 31 in bore 3. These lugsalso form stationary bearings at the. upper ends of the cutters to hold the full lengths of shoulders 34: in interengagement when one or both of the cutters are strained outwardly.

I may, although this is not a necessary clement, form in the opposite inner faces of forks 2 and 2 a pair of slots 32 into which lugs 33 on. the cutters are adapted to fit when the cutters are in their upper expanded positions. These lugs lock each of the cutters directly to the forks 2 and 2 to brace the cutters against the strains of underreaming, particularly to brace the cut ters against outward spreading strains; 111- though these lugs may be'also arranged -to take someof the inthriist and some of the upthrust. j y The surfaces-3O atthe upper opposite sides of the cutter bodies may or may not have a mechanical part to play, according to specific construction and arrangcn'ient.

They 'Ina 'be placed at such an angle that they act against the lower ends of the. body. forks 2 and 2 to assist the expanding action of the cutters; or they maybe placed horizoutally or in any other position, and have no co' action with the body.;; 7

From the foregoing theoperation of my underreamer will be easily};"understood. When the parts are lowered through the easing and reachits lower end, then the upward movement of the cutters causes first an outward expanding movementof the out ters, by action of slot 24 on pin 19. ."lhis outward vexpanding movement is then followed by a straight upward movement of the cutters, during which the surfaces 27 slide upwardly into engagement with the body surfaces 17; the interlocking surfaces 34'liavingbeen thrown into engagement with each other'during the initial outward ex pansive movement of the cutters. The cut ters then move upwardly until their upper ends shoulder up against the downthrust surfaces, 18. In this position lugs 38 in ways 32 may also receive and bear some of the npthrust. In this expanded position of the cutters the parts are all solidly supported and firmly interlocked, as hereinbefore explained. hen the urulerreamer is again drawn upwardly into the casing, the shoulders 29 striking the lower end of the casing force the cutters downwardly on the body:

and when the slots 241mm reached a pos1-' move the inner tion opposite pin 19, then the cutters inwardly to the position shown in Fi surfaces 29 then bearing against the surface of the casing.

It will be understood that the "foregoing description is "given in a typical and not a .limitative sense; that the underrcamer here described is a typitication of forms that may come within the scope of my invention as expressed in the following claims. T her e claims are intended to cover the features of the invention broadly and fundamentally as well as specifically and are not limited against such modifications. changes. etc, as may be made by those skilled in the art. i

Having described a preferred form of my invention, I claim:

1.. An underreamer comprising a body, a pair of overlapping cutters in the body, the cutters bearing inwardly against the body, and overhanging shoulders on the overlapping cutters adapted to intcrengage to'pre-.

vent outward movement of the cutters.

2. An underreamer comprising a body bifurcated at its lower cnd, -the body having forks extending down on opposite sides, and a pair of cutters having fiat shanks 'fitting between the forks, the flat shanks lying side by side against each other, the body having opposite outwardly facing bearings against which the cutters-bear inwardly, and the overlapping cutter shanks havingon their adjacent surfaces overhanging shoulders adapted to interlock to limit the outward movement of the cutters and to hold the cutters to each other. i

3. An underreamer, comprising a body bifurcated at itslower end, a pair of cutters each comprising. a flat shank and a cutter body at the lower outer end of the shank laterally overhanging-the shank, the shanks of the two cutters lying flatly against each other in the fork space of the body. the'underreamer body having opposite outwardly facing bearings near its lower end. the cutter bodies having inwardly facing bearings adapted to bear inwardly against the outwardly facing bearings, and the cutter shanks having overhanging interlocking shoulders adapted to limit the outward movement of the cutters and to hold the cutters laterally together,

l. An underreamer, comprising a body bifurcated at itslower end. a pair of cutters each comprising a flat shank and a cutterbody at the lower outer'end of the shank laterally overhanging the shank, the snanks of the two cutters lying flatly against each other in the fork-space of the body, the inn derream'er body having opposite outwardly facing bearings near its lower end, the cutvertically movable on the body each com-.

prising 'a flat shank and a cutter body at the lower end of the shank laterally overhan ing the shank the shanks of the two cutters lying flatly against each other in the fork-space of the body, the underreammbody having opposite outwardly facing bearings near its lower end, means to cause outward expansion movement of the cutters by virtu of their upward movement, the cutter bodies having inwardly facing bearings moved against the outward facing bearings by the upward and outward movement of the cutters, the cutter shanks having intel-engaging shoulders moved against each other the outward expansion movement of the cutters, and the cutter shanks havingoverhanging interlocking shoulders adapted to limit the outward movement of the, cutters and to hold the cutters latcrallv together.

In witness that I ClfLllTtillQ foregoing l have hereunto subscribed my namcthis find day of July,'1923.' r

ARTHUR Alilil -l( )N. 

